So-called ‘pouch’ batteries, which are also known as ‘envelope’ or ‘packet’ batteries, are increasingly replacing traditional hard-cased batteries in portable electrical applications. In a typical pouch battery, the battery components are overlaid to form a laminated cell structure, folded to a required size and then packaged in a heat-sealable foil. This packaging method offers a light-weight and flexible solution to battery design, and is capable of achieving high energy densities, with the final capacity of the cell being selected according to the desired application.
Pouch batteries can be based on a variety of different cell chemistries, and a range of electrolyte types can be utilised. Lithium primary and secondary batteries, for example, are commonly made according to a pouch design, and dry polymer, gel and liquid electrolytes have all been incorporated into pouch cells.
Despite benefits of weight, size and flexibility, manufacturers are constantly striving to improve the performance of pouch batteries to meet the increasing demands of the portable electronics industry. Moreover, pouch batteries do not offer optimum conditions for battery safety, particularly when attempts are made to scale them up.